* allow telling cmake where to find required fonts in system when user supplies the paths, as suggested by unC0Rr, e.g. -DFONTS_DIRS='/usr/share/fonts/truetype/wqy;/usr/share/fonts/truetype/dejavu'
* the build system will use the paths to lookup fonts and install those not found
* the engine will load the paths into physfs (mountpoint /Fonts) to make the fonts available at runtime
* overriding fonts in packages should be possible again now
